A researcher has refined an attack on wireless routers with poorly implemented versions of the Wi-Fi Protected Setup that allows someone to quickly gain access to a router’s network. The attack exploits weak randomization, or the lack of randomization, in a key used to authenticate hardware PINs on some implementations of Wi-Fi Protected Setup, allowing anyone to quickly collect enough information to guess the PIN using offline calculations. By calculating the correct PIN, rather than attempting to brute-force guess the numerical password, the new attack circumvents defenses instituted by companies. While previous attacks require up to 11,000 guesses—a relatively small number—and approximately four hours to find the correct PIN to access the router’s WPS functionality, the new attack only requires a single guess and a series of offline calculations.